1. Field of the Invention
The present invention relates to a glass-shaping mold used for forming an optical element having a precise shape, and also to a method for manufacturing the mold.
2. Description of the Related Art
As is well known, in the field of plastics molding, high-precision processing technology employing shaping molds is established, and mass production of optical elements having a precise shape (such as diffraction gratings) can be put to practical use. A mold used for this purpose is fabricated by providing a nonelectrolyte Ni—P plating layer on the surface of a base member and processing the plating layer with high precision by use of a turning diamond tool. When this mold is applied to glass-shaping, the Ni—P layer cannot provide reliable releasing characteristics with respect to glass, and a mold-releasing film has to be formed. For example, Jpn. Pat. Appln. KOKAI Publication No. 2002-29772 (Patent Document 1) discloses a mold-releasing film made of W, Pt, Pd or Ir, or an alloy of these metals. In the case of Patent Document 1, however, the higher the shaping temperature is, the worse the surface roughness of the mold-releasing film becomes.